Pedro Brandimarte

Probing the Magnetism of Topological End-States in 5-Armchair Graphene Nanoribbons

ACS Nano - 2020    

^* J.L. and P.B. contributed equally

Abstract

We extensively characterize the electronic structure of ultra-narrow graphene nanoribbons (GNRs) with armchair edges and zig-zag termini that have 5 carbon atoms across their width (5-AGNRs), as synthesised on Au(111). Scanning tunnelling spectroscopy measurements on the ribbons, recorded on both the metallic substrate and a decoupling NaCl layer, show well-defined dispersive bands and in-gap states. In combination with theoretical calculations, we show how these in-gap states are topological in nature and localised at the zig-zag termini of the nanoribbons. Besides rationalising the driving force behind the topological class selection of 5-AGNRs, we also uncover the length-dependent behaviour of these end states which transition from singly occupied spin-split states to a closed-shell form as the ribbons become shorter. Finally, we demonstrate the magnetic character of the end states via transport experiments in a model two-terminal device structure in which the ribbons are suspended between the scanning probe and the substrate that both act as leads.

Press release

Bibtex citation

@Article{Lawrence2020,
  author    = {James Lawrence and Pedro Brandimarte and Alejandro Berdonces-Layunta and Mohammed S. G. Mohammed and Abhishek Grewal and Christopher C. Leon and Daniel Sánchez-Portall and Dimas G. de Oteyza},
  title     = {Probing the Magnetism of Topological End-States in 5-Armchair Graphene Nanoribbons},
  journal   = {ACS Nano},
  year      = {2020},
  volume    = {14},
  number    = {4},
  pages     = {4499--4508},
  issn      = {1936--0851},
  doi       = {10.1021/acsnano.9b10191},
  publisher = {American Chemical Society ({ACS})},
}

Key words

• graphene nanoribbons
• topology
• magnetism
• edge-states
• on-surface synthesis
• scanning tunnelling microscopy
• density functional theory